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United States Patent |
5,503,329
|
Saladino
|
April 2, 1996
|
Automotive thermostat
Abstract
A thermostat for controlling the flow of coolant in an automotive cooling
system comprises a centrally apertured disc forming a valve seat; a saddle
member supported on the disc and straddling the aperture; a valve member
positioned between the saddle and the disc; a spring biasing the valve
member into engagement with the seat; a thermally responsive element for
opening the valve against the spring in response to a predetermined
temperature rise of the coolant; and a plurality of tabs formed in the
disc and concentrically surrounding the valve seat adapted to rupture and
deflect in response to a predetermined system pressure rise to form fluid
passages bypassing the valve, the tabs being defined by score or cut lines
extending partly around each tab.
Inventors:
|
Saladino; Paul D. (P.O. Box 1576, Rochester, NH 03867)
|
Appl. No.:
|
348913 |
Filed:
|
November 25, 1994 |
Current U.S. Class: |
236/34.5; 137/68.27; 236/DIG.2 |
Intern'l Class: |
F01P 007/16 |
Field of Search: |
236/345,DIG. 2
137/68.27
|
References Cited
U.S. Patent Documents
2356958 | Aug., 1944 | Wagenheim.
| |
2418817 | Apr., 1947 | Cantlin | 137/68.
|
2553267 | Oct., 1946 | NeDon.
| |
2842317 | Jul., 1958 | Wood.
| |
2891730 | Jun., 1959 | Wood et al.
| |
3498537 | Mar., 1970 | Wong.
| |
3776457 | Oct., 1971 | Cardi.
| |
4347942 | Nov., 1980 | Jernberg.
| |
4347973 | Jan., 1981 | Jackson.
| |
4353500 | Feb., 1981 | Brown.
| |
4359972 | Jun., 1981 | Calkins.
| |
4479587 | Sep., 1983 | Mundt.
| |
4512491 | Jan., 1984 | DeGood.
| |
4576303 | Feb., 1985 | Mundt.
| |
4691861 | Aug., 1986 | Sliger.
| |
4905722 | Apr., 1989 | Rooker.
| |
5022424 | Oct., 1990 | Reynolds.
| |
5140951 | Aug., 1992 | Carr | 236/DIG.
|
5207744 | Mar., 1992 | Heafner.
| |
Primary Examiner: Tapolcai; William E.
Attorney, Agent or Firm: Shlesinger Arkwright Garvey
Claims
I claim:
1. A thermostat for controlling the flow of coolant in an automotive
cooling system, comprising;
a) a centrally apertured disc forming a valve seat;
b) a saddle member supported on said disc and straddling said aperture;
c) a valve member positioned between said saddle and said disc;
d) a spring biasing said valve member into engagement with said seat;
e) thermally responsive element for opening said valve against said spring
in response to a predetermined temperature rise of the coolant; and
f) a plurality of tabs formed in said disc and concentrically surrounding
said valve seat adapted to rupture and deflect in response to a
predetermined system pressure rise to form fluid passages bypassing said
valve, said tabs being defined by score lines extending partially around
each tab and through the thickness of said disc such that said tabs remain
secured to said disc after rupturing.
Description
FIELD OF THE INVENTION
The present invention relates to an automotive thermostat with an emergency
normally closed bypass that is caused to open to insure coolant flow
through the system when the thermostat fails in the closed position and
where the bypass is integral with the thermostat.
BACKGROUND OF THE INVENTION
As is well known to persons active in the automotive repair business, the
most frequent cause of problems in the cooling systems of automobiles is
failure of the thermostat in a closed position. Invariably this causes
overheating plus a rise in pressure of the cooling system usually
sufficient to rupture either a radiator or heater hose. Whenever this
happens, the thermostat must be removed or replaced and the hose replaced
or patched before the car can be driven.
Prior art attempts to solve this problem include thermostats specifically
designed to "fail safe" by various means to insure that the valve remains
in an open position rather than a closed position when the thermostat
fails due to corrosion or one reason or another. Examples of such
structures may be found in any one of the following prior U.S. Pat. Nos.
2,356,958; 2,842,317; 2,891,730; and 3,498,537. For one reason or another
however, such valve structures have not found wide spread commercial
acceptance whether due to cost of manufacture or inconsistent operational
results or both.
Accordingly, the problem remains to produce a thermostat at reasonable
competitive cost with conventional thermostats, which will give comparable
service lifetime to conventional thermostats and yet which when it fails,
will not result in blockage of coolant circulation with the attendant
problems which inevitably follow.
OBJECTS AND SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an automotive
thermostat that provides a bypass for coolant flow when the valve fails in
the closed position.
It is another object of the present invention to provide an automotive
thermostat that includes an integral bypass for the coolant flow.
It is still another object of the present invention to provide an
automotive thermostat that provides a bypass for the coolant flow that is
relatively inexpensive to manufacture.
It is yet another object of the present invention to provide an automotive
thermostat that is constructed with all outward appearances as
conventional thermostats which are in widespread commercial use throughout
this country today.
In summary, the present invention provides an automotive thermostat that
includes a centrally apertured disc forming a valve seat and a saddle
member straddling the aperture and providing a support for a valve member
which is spring biased into engagement with the seat, but which will open
against the force of the biasing spring in response to a predetermined
temperature rise. In accordance with the present invention, the apertured
disc at the time that it is formed in the manufacturing operation, will be
provided with a series of concentrically arranged, preferably
substantially circular score or cut lines to define a series of tab
members. Such tab members, in response to a predetermined pressure rise in
the system such as would be caused by a thermostat failing in the closed
position, will be deflected out of the plane of the disc by reason of
rupture from the score or cut lines thereby to form a series of fluid
passageways bypassing the main valve.
These and other objects of the present invention will become apparent from
the following detailed description.
BRIEF DESCRIPTIONS OF THE DRAWINGS
FIG. 1 is a side elevational view, with portion shown in cross-section, of
a thermostat made in accordance with the present invention.
FIG. 2 is a top plan view of FIG. 1.
FIG. 3 is a fragmentary enlarged cross-sectional view taken along line 3--3
of FIG. 2, showing the tabs made in accordance with the present invention
in the closed position.
FIG. 4 is a fragmentary enlarged cross-sectional view of another embodiment
of the tabs made in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
As shown in the drawing, a thermostat R made in accordance with the present
invention includes a disc 10 having a central aperture 12. The disc 10
forms the seat for a valve member 14 which is supported by a saddle member
16 and biased by a spring 18 into engagement with the valve seat. A
thermal element 20 is operative when the automotive coolant reaches a
predetermined temperature to open the valve against the force of the
biasing spring 18 and permits coolant flow throughout the system.
In accordance with the present invention, a series of preferably circular
tabs 22 are formed in the disc 10 and arranged concentrically around the
central aperture 12. The tab 22 are formed in the disc 10 by die pressed
score lines 24 which preferably extend somewhat less than 360.degree.
around the tab, as best shown in FIGS. 2 and 3. While it is possible and
certainly within the scope of the present invention to have the score
lines extend a full 360.degree., it is thought preferable to leave a small
section of the tabs 22 without any score lines 24 so that upon a
predetermined pressure rise within the system, the tabs 22 will rupture
from the disc 10 on the score lines 24 but remain attached thereto by the
unscored portion which acts as a hinge. Deflection of the tabs 22 out of
the plane of the disc 10 thus results in a series of passageways 23 which
bypass the main valve, as best shown in FIG. 1, and therefore permits
continued operation of the vehicle without the overheating and pressure
rise which would otherwise occur when the thermostat fails in a closed
position.
The tabs 22 may also be formed by cut lines 26 that go through the
thickness of the disc 10, as best shown in FIG. 4. The cut lines do not
extend a full 360.degree. to hold the tabs 22 in place prior to and after
being deformed by a predetermined pressure rise in the system. The cut
lines 26 insure that the tabs 22 will open up with relatively less
pressure within the system.
Since the disc 10 of a conventional thermostat is manufactured by a
stamping operation, it would be a simple matter to redesign the stamping
die so that the disc 10 could be formed on a mass production basis and at
a minimum cost.
While this invention has been described as having preferred design, it is
understood that it is capable of further modification, uses and/or
adaptations of the invention following in general the principle of the
invention and including such departures from the present disclosure as
come within known or customary practice in the art to which the invention
pertains, and as may be applied to the essential features set forth, and
fall within the scope of the invention or the limits of the appended
claims.
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